t_getinfo(3N)t_getinfo(3N)NAMEt_getinfo - get protocol-specific service information
SYNOPSIS
#ifdef _XOPEN_SOURCE
#include <xti.h>
#else
#include <tiuser.h>
#endif
int t_getinfo(fd, info)
int fd;
struct t_info *info;
DESCRIPTION
This function returns the current characteristics of the underlying
transport protocol associated with file descriptor fd. The info
structure is used to return the same information returned by t_open.
This function enables a transport user to access this information during
any phase of communication.
This argument points to a t_info structure, which contains the following
members:
long addr;/* max size of the transport protocol address */
long options;/* max number of bytes of protocol-specific options */
long tsdu;/* max size of a transport service data unit (TSDU) */
long etsdu;/* max size of an expedited transport service data unit (ETSDU) */
long connect;/* max amount of data allowed on connection establishment functions */
long discon;/* max amount of data allowed on t_snddis and t_rcvdis functions */
long servtype;/* service type supported by the transport provider */
#ifdef _XOPEN_SOURCE
long flags;/* other info about the transport provider */
#endif
The values of the fields have the following meanings:
addr A value greater than or equal to zero indicates the maximum
size of a transport protocol address; a value of -1
specifies that there is no limit on the address size; and a
value of -2 specifies that the transport provider does not
provide user access to transport protocol addresses.
options A value greater than or equal to zero indicates the maximum
number of bytes of protocol-specific options supported by
the provider; a value of -1 specifies that there is no
limit on the option size; and a value of -2 specifies that
the transport provider does not support user-settable
options.
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tsdu A value greater than zero specifies the maximum size of a
transport service data unit (TSDU); a value of zero
specifies that the transport provider does not support the
concept of TSDU, although it does support the sending of a
data stream with no logical boundaries preserved across a
connection; a value of -1 specifies that there is no limit
on the size of a TSDU; and a value of -2 specifies that the
transfer of normal data is not supported by the transport
provider.
etsdu A value greater than zero specifies the maximum size of an
expedited transport service data unit (ETSDU); a value of
zero specifies that the transport provider does not support
the concept of ETSDU, although it does support the sending
of an expedited data stream with no logical boundaries
preserved across a connection; a value of -1 specifies that
there is no limit on the size of an ETSDU; and a value of
-2 specifies that the transfer of expedited data is not
supported by the transport provider.
connect A value greater than or equal to zero specifies the maximum
amount of data that may be associated with connection
establishment functions; a value of -1 specifies that there
is no limit on the amount of data sent during connection
establishment; and a value of -2 specifies that the
transport provider does not allow data to be sent with
connection establishment functions.
discon A value greater than or equal to zero specifies the maximum
amount of data that may be associated with the t_snddis and
t_rcvdis functions; a value of -1 specifies that there is
no limit on the amount of data sent with these abortive
release functions; and a value of -2 specifies that the
transport provider does not allow data to be sent with the
abortive release functions.
servtype This field specifies the service type supported by the
transport provider, as described below.
flags If _XOPEN_SOURCE is defined, then this structure element
will exist. This is a bit field used to specify other
information about the transport provider. If the
T_SENDZERO bit is set in flags, this indicates that the
underlying transport provider supports the sending of
zero-length TSDUs. Following is a dicussion of the
separate issue of zero-length fragments within a TSDU.
Sending data of zero octets:
The transport service definition, both in connection-
oriented mode and in connectionless mode, does not permit
sending a TSDU of zero octets. So, in connectionless mode,
if the len parameter is set to zero, the t_sndudata() call
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will always return unsuccessfully with -1 and t_errno set
to TBADDATA. In connection-oriented mode, if the nbytes
parameter is set to zero, the t_snd() call will return with
-1 and t_errno set to TBADDATA if either the T_MORE flag is
set or the T_MORE flag is not set and the preceding t_snd()
call completed a TSDU or ETSDU (that is, the call has
requested sending a zero byte TSDU or ETSDU.
If a transport user is concerned with protocol independence, the above
sizes may be accessed to determine how large the buffers must be to hold
each piece of information. Alternatively, the t_alloc function may be
used to allocate these buffers. An error will result if a transport user
exceeds the allowed data size on any function. The value of each field
may change as a result of option negotiation, and t_getinfo enables a
user to retrieve the current characteristics.
The servtype field of info may specify one of the following values on
return:
T_COTS The transport provider supports a connection-mode service
but does not support the optional orderly release
facility.
T_COTS_ORD The transport provider supports a connection-mode service
with the optional orderly release facility.
T_CLTS The transport provider supports a connectionless-mode
service. For this service type, t_open will return -2 for
etsdu, connect, and discon.
This function resides within both the X/Open compliant libxnet and the
SVR4 compliant libnsl Network Services libraries. Network Services
applications which require X/Open compliance must link-load with -lxnet.
Network Services applications which require SVR4 compliance must link-
load with -lnsl.
On failure, t_errno may be set to one of the following:
TBADF The specified file descriptor does not refer to a
transport endpoint.
TSYSERR A system error has occurred during execution of this
function.
SEE ALSOt_alloc(3N), t_open(3N)DIAGNOSTICSt_getinfo returns 0 on success and -1 on failure and t_errno is set to
indicate the error.
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